Acta Paediatr 81: 1040-1. 1992
SHORT COMMUNICATION
Relationship between low birth weight and respiratory symptoms in a cohort of primary school children Th Frischer, J Kuehr, R Meinert, W Karmaus, R Barth, E Hermann-Kunz and R Urbanek University Children’s Hospital, FreiburglBreisgau. Germany
It has been shown that a low birth weight (LBW) is one bronchitis. Chronic respiratory symptoms analysed factor which determines respiratory health in later were: “When suffering from a cold, does your child childhood (1, 2). We investigated the relationship frequently cough for longer than 14 days?” These between LBW and the prevalence of chronic respiratory children were referred to as having prolonged cough. symptoms at school age in an ongoing cohort study on Cough after exercise was defined as an affirmative the development of asthma in south-western Germany. answer to “Does your child cough after exercise or when To obtain a representative population sample, the exposed to cold air or fog?” and wheeze by “Have you parents of all children entering primary school in three ever heard a wheezing or whistling noise in your child’s towns were invited to participate. Written consent was breathing?’ A standardized skin-prick test with seven common obtained from the parents of all participants. A parental questionnaire was used to obtain informa- aeroallergens, a positive (histamine 10 mg/ml) and a tion on parental education, parental smoking and the negative (NaCl) control was performed. Wheals were parents’ history of allergic disease (hayfever or asthma). measured after 15 min and scored positive if they The child’s birth weight was recorded. A history of measured at least 2 mm in diameter. Children with at mechanical ventilation after birth was found in 18 least one positive reaction to any of the allergens were children. Validation by medical records demonstrated classified as atopic. T o obtain information on bronchial that 50% of these children had required mechanical hyperresponsiveness, an exercise-challenge test was ventilation for a period of two days to four months: the completed. The children underwent a physical examinother 50% had required oxygen therapy (50-70%) for ation and their heights (cm) were recorded. Peak one to five days. Hence, all these children were classified expiratory flow rate (PEFR) was recorded before a 6as having had neonatal respiratory illness (NRI). A min exercise period and 3, 6 and 9 min thereafter. lifetime prevalence of asthma was based on a medical Children with a 2 15% decrease of PEFR before practitioner’s diagnosis of asthma or recurrent wheezy exercise to the value 3 min after exercise were considered
Table 1. Results of logistic regression analyses.
Dependent variables Cough after exercise
Independent variables Birth weight < 2500 g Maternal smoking During pregnancy Child’s first year Current High educational level Parental history of allergic disease > 5 respiratory illnesses during study year Atopy (skin test positive) Bronchial hyperresponsiveness (decrease in PEFR 2 15% after exercise) Female sex OR =Odds ratio; PEFR = peak expiratory flow rate.
Prolonged cough
OR
p value
OR
p value
Wheeze OR p value
2.09
0.02
1.1
0.64
1.57
0.09
0.84 0.93 1.39 0.80 1.17 3.38 1.51 2.75 0.68
0.58 0.82 0.17 0.03 0.41 0.0001 0.04 0.0003 0.03
1.09 0.95 1.21 0.88 1.43 5.18 1.25 0.98 1.22
0.62 0.59 0.47 0.27 0.07 0.0001 0.28 0.92 0.26
0.72 1.49 0.96 1.07 1.19 2.11 1.71 1.9 0.75
0.18 0.1 0.81 0.38 0.23 0.0001 0.0005 0.01 0.03
ACTA PEDIATR 81 (1992)
LB W and respiratory symptoms in primary school children
1041
to have bronchial hyperresponsiveness. The assessment findings by Chan et al. (2) who observed that neonatal of risk factors for respiratory symptoms was based on respiratory health in LBW children is not a major logistic regressions and provided odds ratios and 95% determinant of respiratory symptoms at school age. Recent studies support the hypothesis that functional confidence intervals (CI). Of 2604 families contacted, 1812 (69.6%) partici- or parenchymal impairments may precede respiratory pated. A birth weight less than 2500 g was recorded in illness in early infancy and might be consequent to 104 children (41 girls and 63 boys). Asthma was antenatal factors like maternal smoking during pregreported significantly more often in the LBW children nancy (3,4). Such a phenomenon could be an explana(18% versus 11%; p
SHORT COMMUNICATION
Relationship between low birth weight and respiratory symptoms in a cohort of primary school children Th Frischer, J Kuehr, R Meinert, W Karmaus, R Barth, E Hermann-Kunz and R Urbanek University Children’s Hospital, FreiburglBreisgau. Germany
It has been shown that a low birth weight (LBW) is one bronchitis. Chronic respiratory symptoms analysed factor which determines respiratory health in later were: “When suffering from a cold, does your child childhood (1, 2). We investigated the relationship frequently cough for longer than 14 days?” These between LBW and the prevalence of chronic respiratory children were referred to as having prolonged cough. symptoms at school age in an ongoing cohort study on Cough after exercise was defined as an affirmative the development of asthma in south-western Germany. answer to “Does your child cough after exercise or when To obtain a representative population sample, the exposed to cold air or fog?” and wheeze by “Have you parents of all children entering primary school in three ever heard a wheezing or whistling noise in your child’s towns were invited to participate. Written consent was breathing?’ A standardized skin-prick test with seven common obtained from the parents of all participants. A parental questionnaire was used to obtain informa- aeroallergens, a positive (histamine 10 mg/ml) and a tion on parental education, parental smoking and the negative (NaCl) control was performed. Wheals were parents’ history of allergic disease (hayfever or asthma). measured after 15 min and scored positive if they The child’s birth weight was recorded. A history of measured at least 2 mm in diameter. Children with at mechanical ventilation after birth was found in 18 least one positive reaction to any of the allergens were children. Validation by medical records demonstrated classified as atopic. T o obtain information on bronchial that 50% of these children had required mechanical hyperresponsiveness, an exercise-challenge test was ventilation for a period of two days to four months: the completed. The children underwent a physical examinother 50% had required oxygen therapy (50-70%) for ation and their heights (cm) were recorded. Peak one to five days. Hence, all these children were classified expiratory flow rate (PEFR) was recorded before a 6as having had neonatal respiratory illness (NRI). A min exercise period and 3, 6 and 9 min thereafter. lifetime prevalence of asthma was based on a medical Children with a 2 15% decrease of PEFR before practitioner’s diagnosis of asthma or recurrent wheezy exercise to the value 3 min after exercise were considered
Table 1. Results of logistic regression analyses.
Dependent variables Cough after exercise
Independent variables Birth weight < 2500 g Maternal smoking During pregnancy Child’s first year Current High educational level Parental history of allergic disease > 5 respiratory illnesses during study year Atopy (skin test positive) Bronchial hyperresponsiveness (decrease in PEFR 2 15% after exercise) Female sex OR =Odds ratio; PEFR = peak expiratory flow rate.
Prolonged cough
OR
p value
OR
p value
Wheeze OR p value
2.09
0.02
1.1
0.64
1.57
0.09
0.84 0.93 1.39 0.80 1.17 3.38 1.51 2.75 0.68
0.58 0.82 0.17 0.03 0.41 0.0001 0.04 0.0003 0.03
1.09 0.95 1.21 0.88 1.43 5.18 1.25 0.98 1.22
0.62 0.59 0.47 0.27 0.07 0.0001 0.28 0.92 0.26
0.72 1.49 0.96 1.07 1.19 2.11 1.71 1.9 0.75
0.18 0.1 0.81 0.38 0.23 0.0001 0.0005 0.01 0.03
ACTA PEDIATR 81 (1992)
LB W and respiratory symptoms in primary school children
1041
to have bronchial hyperresponsiveness. The assessment findings by Chan et al. (2) who observed that neonatal of risk factors for respiratory symptoms was based on respiratory health in LBW children is not a major logistic regressions and provided odds ratios and 95% determinant of respiratory symptoms at school age. Recent studies support the hypothesis that functional confidence intervals (CI). Of 2604 families contacted, 1812 (69.6%) partici- or parenchymal impairments may precede respiratory pated. A birth weight less than 2500 g was recorded in illness in early infancy and might be consequent to 104 children (41 girls and 63 boys). Asthma was antenatal factors like maternal smoking during pregreported significantly more often in the LBW children nancy (3,4). Such a phenomenon could be an explana(18% versus 11%; p
